The present invention is in the field of power distribution systems and, more particularly, power distribution systems which operate in vehicles such as aircraft.
In typical prior art aircraft, power distribution control is performed with two or more independent systems which are distinctly different from one another. A first system may control primary power distribution. Primary power distribution may comprise wiring and contactors for high amperage circuitry. This high amperage circuitry may be considered electrical trunk lines. A second system may control secondary power distribution on relatively low amperage branch circuitry. Some control units for aircraft secondary power systems are typically configured as modules which can be replaced as needed. These replaceable modules are referred to as “line replaceable modules” or LRM's.
In many prior art aircraft, primary and secondary power distribution control systems are located close to one another in a dedicated portion of the aircraft. The dedicated control portion of the aircraft might be provided with a single dedicated fire suppression system. This arrangement has been provided as an important safety feature in prior art aircraft.
In some newer aircraft designs, it is desirable to position LRM's in various locations close to points in an aircraft at which secondary power is required. Primary power distribution controls may remain located in a single dedicated portion of the aircraft. Thus in newer aircraft designs, LRM's may be considered to be remotely located. Use of remotely located LRM's provides for a reduction in the amount and weight of wiring used in an aircraft. But use of remotely located LRM's produces a new set of fire safety issues.
Safety standards for aircraft require that all electrical controls (including secondary controls) must be provided with dedicated fire suppression. Thus each remotely located LRM or remotely located group of LRM's must be provided with a fire suppression system.
Fire suppression for remotely located LRM's has typically been provided by enclosing the LRM's in a fire containment enclosure. In some case, an LRM enclosure may not be designed for fire containment, but an external fire detection and extinguishing may be provided to prevent propagation of fire. Fire containment enclosures or use of fire detection/extinguishing systems add cost and weight to an aircraft. Furthermore, because LRM's produce heat during their operation, the fire containment enclosures must be provided with cooling systems that can carry away this heat. In that regard, the prior art fire containment enclosures may be considered to be heat-retaining enclosures. Cooling systems required to dissipate such retained heat add even more weight and cost.
Because of cost and weight concerns, remotely located LRM's may be grouped together in secondary electric power distribution centers which are placed in fire-containment enclosures. Because of cost and weight considerations only a few of these secondary electric power distribution centers are used in prior art aircraft. Consequently some of the LRM's may be positioned in non-optimum locations.
As can be seen, there is a need to provide a system of power distribution control which accommodates optimum distribution of remotely located LRM's within an aircraft while providing the LRM's with fire suppression protection. Additionally, there is a need to provide such fire suppression protection without use of heat retaining containment enclosures.